1. Field
The disclosure relates generally to X-ray diagnostic units and more particularly to an X-ray source for a mobile X-ray diagnostic unit with a C-arm.
2. Description of the Related Art
Various types of mobile X-ray diagnostic units are known. For example, German Patent No. DE 44 23 359 owned by the assignee of the present application describes an X-ray diagnostic unit with a C-arm that can be adjusted in multiple ways. An X-ray source and an X-ray receiver are arranged at opposite ends of the C-arm. In some embodiments of this unit, some or all of the adjustment axes are equipped with incremental encoders. Such an X-ray diagnostic unit advantageously allows the recording of 2-D X-ray projection images with known projection geometry, from which a 3-D X-ray model can be reconstructed.
Some X-ray diagnostic units suffer from disadvantages. For example, the angular range of movement of the C-arm along its periphery (orbital motion) may be less than 180° in some implementations (e.g., roughly 130°). In some mobile X-ray diagnostic units, if the angular range for the orbital motion were increased to 180° with otherwise equal dimensions of the C-arm, then the opening width between the X-ray source and the X-ray receiver would be reduced. This could, in some cases, substantially reduce the positioning ability of the diagnostic unit. Although the diameter of the C-arm may be increased to increase the opening width, this arrangement generally is not preferred for mobile equipment because of the corresponding increase in weight and decrease in mechanical stability due to the larger C-arm.
Various arrangements for X-ray diagnostic units are known. For example, X-ray diagnostic units with C-arms in which the X-ray source and the X-ray receiver are arranged inside the C-arm are described in U.S. Pat. No. 6,880,691 and French laid-open application FR 2 671 507 A.
U.S. Pat. No. 6,364,526 and French laid-open application FR 2 342 704 A describe X-ray diagnostic units in which the X-ray receiver and the X-ray source are located on a side of the C-arm. The X-ray receiver and source can be displaced outward from the center point of the C-arm sufficiently that the opening width is not impaired by these components. The disclosed asymmetrical arrangement of these diagnostic units is disadvantageous, because the lateral extent of the C-arm with the X-ray source is enlarged and the positioning ability is impaired, especially for under-the-table uses.
United Kingdom Patent GB 351,534 A describes an example of a mobile X-ray source in which an X-ray tube, preferably in an insulating oil container, is connected via a high voltage cable to a high-voltage generator. The high-voltage cable is not very flexible, particularly for voltages in the range of about 80 kV, and is difficult to accommodate given the constricted space conditions in the interior of a mobile X-ray diagnostic unit.
A compact X-ray radiator for a mobile X-ray diagnostic unit is disclosed in German Patent DE 198 24 008 C2. The diagnostic unit has an X-ray tube and a high-voltage generator in an oil-filled vessel, which is arranged at one end of the C-arm and outside the area of the guide rails in the circumferential direction.
German Utility Model No. DE 298 02 014 U1 discloses a mobile X-ray diagnostic unit with a C-arm that has an X-ray radiator at one end, with the available space of the C-frame used for running the cables.